Question

Mary invested $200 for 3 years at 5% per annum.John invested $300 at the same rate. If they both received the same amount f money in interest, fo how man years did John invest his money?

Answer 1

Explanation:

To find the number of years John invested his money, we can set up an equation using the formula for simple interest:

Simple Interest = Principal × Rate × Time

Let's calculate the interest earned by Mary and John separately.

For Mary:

Principal = $200

Rate = 5% per annum = 0.05

Time = 3 years

Interest earned by Mary = Principal × Rate × Time

= $200 × 0.05 × 3

= $30

For John:

Principal = $300

Rate = 5% per annum = 0.05

Time = unknown

Interest earned by John = Principal × Rate × Time

= $300 × 0.05 × Time

Since they both received the same amount of interest, we can equate their interest amounts:

$30 = $300 × 0.05 × Time

Simplifying the equation:

30 = 15Time

Dividing both sides by 15:

Time = 2

Therefore, John invested his money for 2 years in order to receive the same amount of interest as Mary.